(Left to right) Vickie Naylor, Bernadine Clay, and Donna Maxey read a memory prompt as they take part in the Sharing History through Active Reminiscence and Photo-Imagery (SHARP) study, September 20, 2017.
That your risk of Alzheimer’s disease depends on your salary, what you ate as a child, or the block where you live may seem implausible. But researchers are discovering that social determinants of health (SDOH) play an outsized role in Alzheimer’s disease and related dementias, possibly more than age, and new strategies are emerging for how to address these factors.
At the 2022 Alzheimer’s Association International Conference, a series of presentations offered evidence that a string of socioeconomic factors—such as employment status, social support networks, education and home ownership—significantly affected dementia risk, even when adjusting data for genetic risk. What’s more, memory declined more rapidly in people who earned lower wages and slower in people who had parents of higher socioeconomic status.
In 2020, a first-of-its kind study in JAMA linked Alzheimer’s incidence to “neighborhood disadvantage,” which is based on SDOH indicators. Through autopsies, researchers analyzed brain tissue markers related to Alzheimer’s and found an association with these indicators. In 2022, Ryan Powell, the lead author of that study, published further findings that neighborhood disadvantage was connected with having more neurofibrillary tangles and amyloid plaques, the main pathological features of Alzheimer's disease.
As of yet, little is known about the biological processes behind this, says Powell, director of data science at the Center for Health Disparities Research at the University of Wisconsin School of Medicine and Public Health. “We know the association but not the direct causal pathway.”
The corroborative findings keep coming. In a Nature study published a few months after Powell’s study, every social determinant investigated affected Alzheimer’s risk except for marital status. The links were highest for income, education, and occupational status.
Clinical trials on new Alzheimer’s medications get all the headlines but preventing dementia through policy and public health interventions should not be underestimated.
The potential for prevention is significant. One in three older adults dies with Alzheimer's or another dementia—more than breast and prostate cancers combined. Further, a 2020 report from the Lancet Commission determined that about 40 percent of dementia cases could theoretically be prevented or delayed by managing the risk factors that people can modify.
Take inactivity. Older adults who took 9,800 steps daily were half as likely to develop dementia over the next 7 years, in a 2022 JAMA study. Hearing loss, another risk factor that can be managed, accounts for about 9 percent of dementia cases.
Clinical trials on new Alzheimer’s medications get all the headlines but preventing dementia through policy and public health interventions should not be underestimated. Simply slowing the course of Alzheimer’s or delaying its onset by five years would cut the incidence in half, according to the Global Council on Brain Health.
Minorities Hit the Hardest
The World Health Organization defines SDOH as “conditions in which people are born, work, live, and age, and the wider set of forces and systems shaping the conditions of daily life.”
Anyone who exists on processed food, smokes cigarettes, or skimps on sleep has heightened risks for dementia. But minority groups get hit harder. Older Black Americans are twice as likely to have Alzheimer’s or another form of dementia as white Americans; older Hispanics are about one and a half times more likely.
This is due in part to higher rates of diabetes, obesity, and high blood pressure within these communities. These diseases are linked to Alzheimer’s, and SDOH factors multiply the risks. Blacks and Hispanics earn less income on average than white people. This means they are more likely to live in neighborhoods with limited access to healthy food, medical care, and good schools, and suffer greater exposure to noise (which impairs hearing) and air pollution—additional risk factors for dementia.
Related Reading: The Toxic Effects of Noise and What We're Not Doing About it
Plus, when Black people are diagnosed with dementia, their cognitive impairment and neuropsychiatric symptom are more advanced than in white patients. Why? Some African-Americans delay seeing a doctor because of perceived discrimination and a sense they will not be heard, says Carl V. Hill, chief diversity, equity, and inclusion officer at the Alzheimer’s Association.
Misinformation about dementia is another issue in Black communities. The thinking is that Alzheimer’s is genetic or age-related, not realizing that diet and physical activity can improve brain health, Hill says.
African Americans are severely underrepresented in clinical trials for Alzheimer’s, too. So, researchers miss the opportunity to learn more about health disparities. “It’s a bioethical issue,” Hill says. “The people most likely to have Alzheimer’s aren’t included in the trials.”
The Cure: Systemic Change
People think of lifestyle as a choice but there are limitations, says Muniza Anum Majoka, a geriatric psychiatrist and assistant professor of psychiatry at Yale University, who published an overview of SDOH factors that impact dementia. “For a lot of people, those choices [to improve brain health] are not available,” she says. If you don’t live in a safe neighborhood, for example, walking for exercise is not an option.
Hill wants to see the focus of prevention shift from individual behavior change to ensuring everyone has access to the same resources. Advice about healthy eating only goes so far if someone lives in a food desert. Systemic change also means increasing the number of minority physicians and recruiting minorities in clinical drug trials so studies will be relevant to these communities, Hill says.
Based on SDOH impact research, raising education levels has the most potential to prevent dementia. One theory is that highly educated people have a greater brain reserve that enables them to tolerate pathological changes in the brain, thus delaying dementia, says Majoka. Being curious, learning new things and problem-solving also contribute to brain health, she adds. Plus, having more education may be associated with higher socioeconomic status, more access to accurate information and healthier lifestyle choices.
New Strategies
The chasm between what researchers know about brain health and how the knowledge is being applied is huge. “There’s an explosion of interest in this area. We’re just in the first steps,” says Powell. One day, he predicts that physicians will manage Alzheimer’s through precision medicine customized to the patient’s specific risk factors and needs.
Raina Croff, assistant professor of neurology at Oregon Health & Science University School of Medicine, created the SHARP (Sharing History through Active Reminiscence and Photo-imagery) walking program to forestall memory loss in African Americans with mild cognitive impairment or early dementia.
Participants and their caregivers walk in historically black neighborhoods three times a week over six months. A smart tablet provides information about “Memory Markers” they pass, such as the route of a civil rights march. People celebrate their community and culture while “brain health is running in the background,” Croff says.
Photos and memory prompts engage participants in the SHARP program.
OHSU/Kristyna Wentz-Graff
The project began in 2015 as a pilot study in Croff’s hometown of Portland, Ore., expanded to Seattle, and will soon start in Oakland, Calif. “Walking is good for slowing [brain] decline,” she says. A post-study assessment of 40 participants in 2017 showed that half had higher cognitive scores after the program; 78 percent had lower blood pressure; and 44 percent lost weight. Those with mild cognitive impairment showed the most gains. The walkers also reported improved mood and energy along with increased involvement in other activities.
It’s never too late to reap the benefits of working your brain and being socially engaged, Majoka says.
In Milwaukee, the Wisconsin Alzheimer’s Institute launched the The Amazing Grace Chorus® to stave off cognitive decline in seniors. People in early stages of Alzheimer’s practice and perform six concerts each year. The activity provides opportunities for social engagement, mental stimulation, and a support network. Among the benefits, 55 percent reported better communication at home and nearly half of participants said they got involved with more activities after participating in the chorus.
Private companies are offering intervention services to healthcare providers and insurers to manage SDOH, too. One such service, MyHello, makes calls to at-risk people to assess their needs—be it food, transportation or simply a friendly voice. Having a social support network is critical for seniors, says Majoka, noting there was a steep decline in cognitive function among isolated elders during Covid lockdowns.
About 1 in 9 Americans age 65 or older live with Alzheimer’s today. With a surge in people with the disease predicted, public health professionals have to think more broadly about resource targets and effective intervention points, Powell says.
Beyond breakthrough pills, that is. Like Dorothy in Kansas discovering happiness was always in her own backyard, we are beginning to learn that preventing Alzheimer’s is in our reach if only we recognized it.
Sarah Watts's son Henry was born with spina bifida and can't stand or walk without assistance.
When our son Henry, now six, was diagnosed with spina bifida at his 20-week ultrasound, my husband and I were in shock. It took us more than a few minutes to understand what the doctor was telling us.
When Henry was diagnosed in 2012, postnatal surgery was still the standard of care – but that was about to change.
Neither of us had any family history of birth defects. Our fifteen-month-old daughter, June, was in perfect health.
But more than that, spina bifida – a malformation of the neural tube that eventually becomes the baby's spine – is woefully complex. The defect, the doctor explained, was essentially a hole in Henry's lower spine from which his spinal nerves were protruding – and because they were exposed to my amniotic fluid, those nerves were already permanently damaged. After birth, doctors could push the nerves back into his body and sew up the hole, but he would likely experience some level of paralysis, bladder and bowel dysfunction, and a buildup of cerebrospinal fluid that would require a surgical implant called a shunt to correct. The damage was devastating – and irreversible.
We returned home with June and spent the next few days cycling between disbelief and total despair. But within a week, the maternal-fetal medicine specialist who diagnosed Henry called us up and gave us the first real optimism we had felt in days: There was a new, experimental surgery for spina bifida that was available in just a handful of hospitals around the country. Rather than waiting until birth to repair the baby's defect, some doctors were now trying out a prenatal repair, operating on the baby via c-section, closing the defect, and then keeping the mother on strict bedrest until it was time for the baby to be delivered, just before term.
This new surgery carried risks, he told us – but if it went well, there was a chance Henry wouldn't need a shunt. And because repairing the defect during my pregnancy meant the spinal nerves were exposed for a shorter amount of time, that meant we'd be preventing nerve damage – and less nerve damage meant that there was a chance he'd be able to walk.
Did we want in? the doctor asked.
Had I known more about spina bifida and the history of its treatment, this surgery would have seemed even more miraculous. Not too long ago, the standard of care for babies born with spina bifida was to simply let them die without medical treatment. In fact, it wasn't until the early 1950s that doctors even attempted to surgically repair the baby's defect at all, instead of opting to let the more severe cases die of meningitis from their open wound. (Babies who had closed spina bifida – a spinal defect covered by skin – sometimes survived past infancy, but rarely into adulthood).
But in the 1960s and 1970s, as more doctors started repairing defects and the shunting technology improved, patients with spina bifida began to survive past infancy. When catheterization was introduced, spina bifida patients who had urinary dysfunction, as is common, were able to preserve their renal function into adulthood, and they began living even longer. Within a few decades, spina bifida was no longer considered a death sentence; people were living fuller, happier lives.
When Henry was diagnosed in 2012, postnatal surgery was still the standard of care – but that was about to change. The first major clinical trial for prenatal surgery and spina bifida, called Management of Myelomeningocele (MOMS) had just concluded, and its objective was to see whether repairing the baby's defect in utero would be beneficial. In the trial, doctors assigned eligible women to undergo prenatal surgery in the second trimester of their pregnancies and then followed up with their children throughout the first 30 months of the child's life.
The results were groundbreaking: Not only did the children in the surgery group perform better on motor skills and cognitive tests than did patients in the control group, only 40 percent of patients ended up needing shunts compared to 80 percent of patients who had postnatal surgery. The results were so overwhelmingly positive that the trial was discontinued early (and is now, happily, the medical standard of care). Our doctor relayed this information to us over the phone, breathless, and left my husband and me to make our decision.
After a few days of consideration, and despite the benefits, my husband and I actually ended up opting for the postnatal surgery instead. Prenatal surgery, although miraculous, would have required extensive travel for us, as well as giving birth in a city thousands of miles from home with no one to watch our toddler while my husband worked and I recovered. But other parents I met online throughout our pregnancy did end up choosing prenatal surgery for their children – and the majority of them now walk with little assistance and only a few require shunting.
Even more amazing to me is that now – seven years after Henry's diagnosis, and not quite a decade since the landmark MOMS trial – the standard of care could be about to change yet again.
Regardless of whether they have postnatal or prenatal surgery, most kids with spina bifida still experience some level of paralysis and rely on wheelchairs and walkers to move around. Now, researchers at UC Davis want to augment the fetal surgery with a stem cell treatment, using human placenta-derived mesenchymal stromal cells (PMSCs) and affixing them to a cellular scaffold on the baby's defect, which not only protects the spinal cord from further damage but actually encourages cellular regeneration as well.
The hope is that this treatment will restore gross motor function after the baby is born – and so far, in animal trials, that's exactly what's happening. Fetal sheep, who were induced with spinal cord injuries in utero, were born with complete motor function after receiving prenatal surgery and PMSCs. In 2017, a pair of bulldogs born with spina bifida received the stem cell treatment a few weeks after birth – and two months after surgery, both dogs could run and play freely, whereas before they had dragged their hind legs on the ground behind them. UC Davis researchers hope to bring this treatment into human clinical trials within the next year.
A century ago, a diagnosis of spina bifida meant almost certain death. Today, most children with spina bifida live into adulthood, albeit with significant disabilities. But thanks to research and innovation, it's entirely possible that within my lifetime – and certainly within Henry's – for the first time in human history, the disabilities associated with spina bifida could be a thing of the past.